Should I replace TPS if truck is running fine? CEL is on with code P0120 and P0171

Hey all, I am getting 2 codes: P0171 and P0120.
I took out my MAF and cleaned it. It looked a bit dirty so i figured maybe this was the issue, but after cleaning it, the CEL is still on and the MAF is working correctly. Now I'm looking into the P0120 code. I've ordered a new TPS from autozone, but I'm wondering if I should even bother replacing the TPS if I don't know if that's going to solve it. The truck runs fine. No idling, stuttering, or jerking. I just want this CEL off before I head out for a long road trip. Any advice is appreciated. Thank you all in advance!

 

I would look into what all the causes for that code could be. Or, if you have a lot of money, just start throwing parts at it until something fixes it.

 

Return the auto zone garbage and use denso parts

 

i ended up unplugging the battery to reset the CEL and I'll just see if it comes back on. truck is running smoothly and idling perfectly which leads me to think the TPS is totally fine.

 

I would say you have two different issues. The 120 code for the TPS may well be resolved by replacing the TPS, but it could also be a bad ground, broken conductor, or one of several other issues. Check your signal to and from the TPS before you fire the parts canon. As for the 171 lean code, as that's only one side of the engine, I don't see how it could possibly be related to a TPS; you need to do a live-data monitor on your fuel trips as a starting point and go from there.

 

most codes that trip a CEL require a reset of the PCM to turn the CEL off, others such evap codes will clear themself. The 2 codes that were set make sense to me as I sit at my keyboard. The PCM reads the inputs from the TPS and the MAF and other sensors and when something doesnt make sense like ... the crank position sensor says the truck is running @ XXX rpm, the TPS says the throttle is WOT but the MAF shows low air flow. It is more complicated than that but you get the picture.

I would look for a leak in the air tube between the MAF and the throttle body first. exhaust leak second.

 

I was just going to ask if you cleared the codes first.

Don't know if this is true, but seems like there are some codes that will never self-clear, and you have to manually clear them. How many miles have you put on it since you cleared the codes? Sometimes it takes a while for the code to show back up.

I would suggest getting your own code reader that can clear them for you. I have this little blue tooth OBDII reader I got off Amazon and Torque Pro on my phone. It works great if for nothing else but a reader and can clear the codes. But you can set up live monitoring of a bunch of ECU data, too (coolant temps, MAF flows, trans temp (in some Tacos), etc...


I've got a trip to Moab coming up in a couple weeks, so I've been driving the Taco around every time I get a chance (it's not my daily driver anymore) so I can find any little issues like that before I head out. Glad I did because I ended up throwing a couple codes a week or so ago. Ended up being something simple (dirty MAF), but I'm glad I had plenty of time to figure it out and troubleshoot, and had time to order parts if I needed.

As for the TPS you bought, are you still running the OEM one or do you have the autozone one on there? My rule of thumb is to go OEM on just about anything to do with the engine, notably anything with moving parts or electricity flowing through it. So if that autozone TPS sensor is in there, I honestly wouldn't expect it to last all that long. The store brand parts rarely do. I'm betting all you'd need to do is clean the original, check your connections, and keep the OEM one.

 

If there was unmetered air being introduced before the throttle-body, then you should have a lean DTC for both banks, not just one.

 

thanks for all the info, so far i've just put 20 miles since i reset the codes and no CEL...yet. will update if anything changes.

 

Twice (once in a Chevy and another time in a Dodge) my engines died suddenly leaving me on the side of the road. Both times no name brand electronic ignition parts failed without warning.